Piston for internal combustion engines



1939- w. BORRMANN ET AL PISTON FOR INTERNAL COMBUSTION ENGINES Filed Oct. 19, 1937 2 Sheets-Sheet 1 Feb. 7, 1939. w. B ORRMANN ET AL PISTON FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed Oct. 19, 1957 M 1 My?! 5 M4.- M W, 0- Wfw Patented Feb. 1,1939

UNITED STATES PATENT OFFICE PISTON non. m'mamr. COMBUSTION ENGINES Waldemar and Albert Keane, Badersleben, Germany 7 Claims.

Pistons for internal combustion engines are not perfect for continuous working owing to corrosion, the possibility of seizing and to a seizing by fusion of the piston and piston rings, the more so as with these inconveniences an excessive consumption in fuel, oil and material is connected. It is also known, that wear of the pistons occurs much more rapidly on the piston head than on the piston body, as the latter is made resilient by i a longitudinal slit. It has been proposed, to avoid wearing of the piston head by equipping it with closed rings, rigidly anchored in the piston body, or by fitting closed rings into the piston head and securely holding them by a cover plate. Rings.

. ifor protecting against fusion and rings for protecting the piston edges have also been proposed. None of these constructions, however, brings the leading piston edge out of the range of the fire, so that the known protecting means cannot give a satisfactory result, the less so as they are not gasand fireproof if protecting rings are employed constructed -after the manner of piston rings. With the pistons of known type it is further not possible to keep the piston guide permanently under oil.

I All these inconveniences are obviated by the invention. In the improved piston for internal combustion engines the piston protecting ring, which resiliently grips around the set-off piston head, forms at the same time an oil ring. The piston guiding begin below'this protectingand oi1-ring,-so that it is protected against the gases from combustion. The closure of the resilient piston protecting-- and oil-ring is fireand gasproof even after the maximum wear, so that the full efliciency of the motor is ensured. To avoid hammering of the protecting ring, it may be securely held in position by a ring-shaped springinsert. Whereas further by the special practical 4o arrangement of the protectingand oil-ring expanding of the piston head can take place without any hindrance, the piston head itself may be made resilient in that at the point of transition from the pistonbody to the piston head two opposite H shaped transverse slits are arranged.

An embodiment of the invention is illustrated,

by way, of example, in the accompanying drawings in which Fig. 1 shows the improved piston inlongitudinal section.

Fig. 2 is a side elevation of Fig. l, the piston rings being omitted.

Fig. 3 shows in longitudinal section, partly broken away, a piston of modified construction. Fig. 4 shows in front elevation the open closure of the protectingand oil-ring for a piston of modified construction.

Fig. 5 is a cross-section on line V--V of Fig. 4. Fig. 6 is a cross-section on line VIVI of Fig. 4.

Fig. 7 is like Fig. 6, the two piston rings engag- 5 ing the one in the other.

Fig. 8 shows the open closure viewed from the inner side of the ring.

Fig. 9 is a section through a piston equipped with protectingand oil-ring according to Figs. 4 to 8.

Fig. 10 shows the spring-insert in top plan view.

Fig. 11 shows a portion of the spring-insert in section.

Fig. 121s a cross-section through the springinsert on line XII-XII of Fig. 10 on considerably enlarged scale.

Figs. 1 to 3 show the simplest form of construction of the improved piston, in which two 'piston ringsa are preserved as well as the vertical -slit b'in the piston body. The arrangement of two parallel transverse slits d, d in the piston head .-c is novel, said transverse slits being connected at the middle by vertical slits d (Fig. 2). Owing to these slits also the piston head is made resilient.

The piston head h is set off, as shown in Fig. 1, and has an annular groove for a protecting ring 9 which is constructed like a resilient piston ring. The edge of the piston head h may be formed by a ring i of harder material than that of the piston as shown in Fig. 3, whereby working of the ring 9 into the piston head when the motor is in operation is prevented. As this hard edge 1 does not touch the cylinder wall, seizing of the piston cannot occur.

Oil channels 7' are formed in the piston head and end in the annular groove 1 which goes over into a bevelled edge It. The protecting ring g has an annular oil groove m 'which is connected by vertical grooves 12. with the annular oil channel 0 formed by the bevelled edge It (Fig. 3). The oil circulates in the grooves m, n and effects cooling of the upper part of the piston, aspermanently fresh oil is admitted which cannotbecon- 'verted into carbon. 7

In the piston shown in Fig. 9 the protecting ring g has two'annular oil grooves m which are connected with the oil channel 0 by vertical grooves 12. These vertical grooves may be mutually displaced. In this protecting. ring the circulation of the oil in the grooves m, n is even better than at the piston shown in Figs. 1 and 3. The oil grooves j lead, in the piston shown in Fig. 9, to a ring channel formed in the piston head in which an insert-spring p is located. The protecting ring g has on the inner side two annular grooves g, 9 (Fig. 7). The upper annular groove g is cut into an extension I formed on one end of the ring and which on the inner side is of semi-circular, shape (Fig. 5). By the groove g two horizontal packing faces 2, 3 are formed in the extension I. On the other end of the ring a cavity 4 of semi-circular cross-section is formed as guide for the pin I (Fig. 6). In the ring end (Fig. 8) a recess 5 is thereby formed and further round packing faces 6, I and two horizontal packing faces 8 which form extension of the faces 2, 3. The faces 2, 3 and 8 hear from above and from below against the upper ring flange h of the piston head.

By the upper annular groove 9' of the protecting ring not only a tight bearing of this ring against the flange h of the piston head is formed, but fire .and gas are prevented from flowing through the closure, even when the two ends of ring 9 do not tightly join, as in this instance the gases from combustion impinge upon pin I which does not let them pass. The gases from combustion can also not pass through the recess 5, as the same is covered by the flange h of the piston headand as further the recess 5 is not wider than the flange h of the piston head so that the faces 2, 3 and8 effect a thorough packing even when the ring g is expanded.

Between the protecting ring and the flange of the piston head suflicient clearance exists that an expansion of the piston head can take place without any'forcible pressing of the protecting ring against the cylinder wall. From the outer side the closure is kept tight by the cylinder wall (Fig. 9).

Whereas in the form of construction shown in Fig. 3 hammering of the protecting ring a is prevented by the hard outer rim i of the piston head, a spring ring p which is undulated and composed of two parts is employed for the same purpose as shown in Fig. 9, each semi-ring being covered by two plates 1', 1'" which are hook-shaped and grip over the rear end of spring p, whereas the front ends are arc-shaped (Fig. 12) in order that the recess g formed in the protecting ring may be easily slipped over the spring ring which then securely holds in position the protecting ring. The oil channels 9' lead directly to the spring ring p and from the same to the oil channel 0. Every half of the spring ring may be loosely connected with the plates 1', r' by pins t flxed on the plate r and by sleeve s flxed on plate 1".

We claim:

1. A piston for internal combustion engines, comprising in combination with the head having several annular grooves, the lowermost groove having a bevelled edge, a protecting ring in the piston head engaging in said annular grooves and having a plurality of oil grooves, the lower side of said protecting ring forming an oil channel with said bevelled edge of said lowermost groove, and vertical oil grooves in said protecting ring connecting said oil channel with said oil grooves in said protecting ring.

2. A piston as specified in claim 1, in which the protecting ring has at one of its ends a pin semicircular on the inner side, and at the other end a semicircular recess, said pin as well as said recess being intersected by the upper annular groove of the protecting ring.

3. A piston as specified in claim 1, in which the protecting ring has at one of its ends a pin semicircular on the inner side, and at the other end a semicircular recess, said pin as well as said recess being intersected by the upper annular groove of the protecting ring, said intersecting groove forming in the pin two horizontal packing faces and in the recess two round packing faces and two horizontal packing faces for said edge of the piston head, so that the packing of said piston head edge remains uninterrupted by a shifting of said pin in its guide.

4. A piston as specified in claim 1 comprising in combination a set-off portion of the piston head, said protecting ring having a flange, and a ring of hard material in said set-01f piston head said flange of said protecting ring bearing against said hard ring.

5. A piston as specified in claim 1, comprising in combination with the protecting ring, a flange on said protecting ring, and an undulated springring in one of the grooves in the piston head and bearing against said flange of said protecting ring.

6. A piston as specified in claim 1, comprising in combination with the protecting ring, a flange on said protecting ring, an undulated spring-ring in one of the grooves in the piston head and bearing against said flange of said protecting ring, and two plates each curved downwards at the end and covering said spring-ring on both sides.

' 7. A piston as specified in claim 1, in which the piston head has two parallel transverse slits and vertical middle slits connecting said transverse slits.

WALDEMAR- BORRMANN. ALBERT KEUNE. 

